Slot punching machine



Nov. 22, 1966 K. GRIESINGER 3,286,566

SLOT PUNCHING MACHINE Filed Feb. 5, 1964 INVENTOR BY Mi ATTORNEYS United States Patent 3,286,566 SLOT PUNCHING MACHINE Karl Griesinger, Goppingen-Jebenhausen, Germany, assignor to Firma L. Schuler AG., Goppingen, Wurttemberg, Germany Filed Feb. 3, 1964, Ser. No. 342,143

Claims priority, application Germany, Feb. 15, 1963,

Sch 32,789 1 Claim. (Cl. 83-'-68) The invention relates to a slot punching machine. With known slot punching machines the ram is driven by means of a two-armed rocking lever. The ram is fastened to the forward end of the rocking lever by means of a thrust member and one end of a connecting rod is engaged by the rear end of the rocking lever, and the other end is driven by means of an eccentric or a crank. At each revolution of the crank or of the eccentric the ram executes one stroke. When the plunger passes through the out six sets of bearing play are operative corresponding to the six joints.

The invention relates to a slot punching machine with a toggle linkage drive, which. consists in the fact that the toggle drive is driven with a rocking movement across its extended position.

The particular advantage of the invention lies in the fact that because for each revolution of a driving shaft, which may be an eccentric shaft or a crank-shaft, two depressions of the ram are obtained, namely one depression of the ram when the toggle link is moved in one direction across the extended position, and a further depression of the ram on the return movement in the converse direction across the extended position.

The advantage that two ram strokes are obtained for each revolution of thedriving shaft also provides the further advantage that the driving shaft has only to rotate at half the rotary speed for the same number of working strokes of the shaft. in the known high-speed slot punching machines. This furthermore means that on stopping the drive only A of the energy must be absorbed and the energy expended on starting the drive can be smaller to a corresponding amount than with comparable slot punching machines. These energy conditions play a considerable part however since slot punching machines, particularly when used for punching motor armature sheets, do not operate continuously for an extended period, but after the punching of the slots in one plate they remain stationary until a new plate has been inserted beneath the punch.

A further advantage of the drive according to the invention lies in the fact that in the lower dead-centre position of the punch the link driving the toggle lever does not have to change its movement and its direction of movement does not vary so that the bottom deadcentre of the punch is traversed very quickly. Reversal in the movement of the link driving the toggle lever is effected only at the end point with the toggle link swung laterally out. The resulting retardation of the drive is thus effected at the top dead-cenre of the punch.

More specifically the present invention relates to a slot punching machine comprising a press frame, a ram movable in said frame, a rocker member pivoted to the frame, a thrust member connecting one arm of the rocker mem her to the ram, said arm and the thrust member forming a toggle linkage, and an operating member linked to another arm of the rocker member for applying a rocking movement thereto, the rocker member and the thrust member being arranged so that the toggle linkage swings across the in-line position intermediately of the rocking movement of the rocker member.

In one embodiment of the invention the rocker member comprises a bell crank in the form of a triangular Patented Nov. 22, 1966 plate, one arm of which is linked to the thrust member and this arm and this member form the toggle linkage, and the other arm is coupled to a connecting rod. The rocker member and the parts connected to it are arranged so that the toggle linkage swings across the in-line position towards end positions on each side of the in-line position, which end positions are attained at the dead centre positions of the operating member.

The construction according to the invention has the advantage that when the punch, carried by the ram, passes through the cut, only three sets of bearing play are operative, namely the play in the joint between the thrust member and the ram, the play between the said member and the rocker member and the play in the bearing for the rocker member. Since the parts do not vary their direction of movement at their instant the speed does not substantially vary at the time of passage of the toggle linkage through its extended position and there is also no bearing lay in the driving members when the punch passes through the cut. The driving members are at midstroke at this instant, the dead-centre of the driving members coinciding with the top dead-centre of the ram and punch. Since also the stoppage of the machine is effected in the top dead-centre position of the ram and punch, that is in a position in which the driving eccentric is near its dead-centre position, only the main shaft has to be brought to a standstill when stopping the machine, as already stated.

The machine must always be stopped in exactly the same position, namely at the top dead-centre of the punch in order that also the automatically supplied plate can always be placed in the correct position on the device which rotates the plate under the punch so that the punch cuts the slots along the edges of the plate at successive strokes.

As a rule the ram drive is synchronised with the drive for this device. The requirement that the machine shall be stopped always in the same position can be satisfied comparatively easily and reliably with the machine according to the invention since, at the top dead-centre of the punch, as stated, all the ram operating parts from the main shaft to the punch are stopped and the main shaft rotates with only a comparatively low speed since, with the construction according to the invention, two ram strokes are executed for each revolution of the driving shaft. The braking and exact stopping of the machine does not therefore involve any difficulties.

This can even be carried out so far that the usual press clutch is entirely omitted and, at the same time as the stoppage of the motor current, the driving shaft can be braked by means of a hand brake or the like.

The saving of a clutch represents furthermore a substantial advantage, not only as regards production costs, but also as regards reduction of the points of wear, of the rotating masses, the reduction in weight, and the amount of space occupied.

Further features of the invention will be apparent from the following description of one constructional form of the invention in conjunction with the claim and the accompanying drawing, in which:

FIG. 1 shows the parts necessary for understanding the invention in side view,

FIG. 2 shows further driving lying behind FIG. 1.

In the embodiment of the invention shown in the drawing, a press frame carries a ram 1 serving for mounting the punch, and is operated by a drive system which includes a thrust member 2 which forms a toggle linkage 6 together with one arm 3 of a rocker member 4 which may be a bell crank in the form of a triangular plate. The rocker member 4 is pivotally mounted on the machine frame by means of a pivot pin 5. The arm 3 parts at a sectional point provided by one corner part of the triangular plate 4 in the embodiment shown forms one section of a toggle linkage, the other section of which is formed by the member 2. A connnecting rod 9 is linked by a joint 8 to the other arm 7 of the rocker member 4 extending oppositely to the arm 3 and on the other side of the axis of the pivot pin 5. The connecting rod is driven from an eccentric 10 mounted on a main driving shaft 11 which is driven through a belt drive 12 from a squirrel cage or other suitable driving motor 13. A brake disc 14 is also mounted on the driving shaft 11 which is engaged by any suitable brake, for example a band brake 15 which can be operated pneumatically, hydraulically or electromagnetically. For example the flow of the pressure medium acting on a piston 17 in a cylinder 16 and connected to the brake band 15 is disposed in the same operating circuit as a control switch for the motor 13.

The foregoing arrangement is shown schematically in FIGURE 2 wherein the operating circuit shown includes a spring-pressed solenoid 19 for controlling a valve member 18 in the fluid line between the fluid pressure source 23 and the cylinder 16. Also included in the operating circuit is a further solenoid 22 whose spring-pressed armature controls a switch 24 for controlling energization of the motor 13. Further comprised in the operating circuit is a current source 21 and a selectively operable switch constituting a common control for the two solenoids 19 and 22.

The eccentricity of the eccentric 10 in relation to the axis of the shaft 11 is so chosen that if the shaft 11 rotates through about 90 from the position shown in FIG. 1, the ram is in its bottom dead-centre position, and thus the toggle linkage 3, 2 is in its extended, in-line position, and that for displacement through 180 relatively to the position shown in FIG. 1, the toggle joint 6 is at the point 6', that is the ram is again in its top dead-centre.

What I claim is:

A slot punching machine comprising a press frame having a base portion and a main driving shaft in said base portion, a ram movable in said frame, a rocker member having a plurality of arms and pivoted to said frame, a thrust member connecting one of said arms to said ram, said one of said arms and the thrust member forming a toggle linkage, and a connecting rod pivotally connected at the upper end thereof to another of said arms, an eccentric member on said main driving shaft, said connecting rod being slidably and rotatably connected at the lower end thereof to said eccentric member, said rocker member, said thrust member and said connecting rod being arranged so that said toggle linkage swings across the in-line position intermediately between the dead-centre positions of said connecting rod and said eccentric member, a driving rmotor, belt connections between said motor and said driving shaft, and poweroperated braking means of said main driving shaft to halt the rotation of the latter, said power-operated braking means including a brake disc on said main driving shaft, a brake band adapted to apply braking force to said brake disc, a hydraulic cylinder having a piston connected to said brake band for applying said braking force, electrical control means for said driving motor, electrical control means for controlling the flow of hydraulic medium to said cylinder, and an electrical switch constituting a common control for both of said electrical control means.

References Cited by the Examiner UNITED STATES PATENTS 299,290 5/1884 Stiles 83-630 2,032,836 3/1936 Criley 7438 2,182,544 12/1939 Murrian et al 83916 X 2,364,334 12/1944 Wold 83630 X 2,722,128 11/1955 Ostwaldt 7438 2,851,888 9/1958 Scholin 83630 X 3,183,743 5/1965 ODonnell et al. 8363O X FOREIGN PATENTS 141,704 8/1953 Sweden.

WILLIAM W. DYER, JR., Primary Examiner.

J. M. MEISTER, Assistant Examiner. 

